1. Field of the Invention
The present invention relates generally to mobile networking, and more particularly, to an authentication and access control system for reducing the time required for a mobile user to authenticate to a new communications network.
2. Description of the Related Art
A user having a network access device (mobile host), who moves from a location covered by the user's home network to another location covered by a foreign access network, can be characterized as “roaming” between networks. Typically, the complicated handoff procedure that enables the mobile host to gain access to the new network can cause QoS problems. When the mobile host moves from the coverage of one network and roams into the coverage of the new or “arriving” network, three basic actions occur to effectuate a handoff: (1) the mobile host authenticates to the arriving network; (2) the arriving network allocates resources for the mobile host; and (3) the departing network releases any resources allocated to the mobile host. When a mobile host authenticates to a foreign network that is under a different administration than the departing network, the authentication step can be relatively time consuming. A typical authentication scenario is illustrated in FIG. 1 for an existing Local Area Network (LAN) access control method based on the 802.1x standard. A mobile host 100 moves within the coverage of a foreign access network having a foreign access point (AP) 102. The AP 102 (or “base station” using cellular terminology) does not enable the mobile host 100 to access the new network until the mobile host has been authenticated by the mobile host's home AAA server 104. Since the mobile host 100 and the foreign AP 102 do not belong to the same network, the AP 102 cannot locally authenticate the mobile host 100. In these cases, the AP 102 forwards the mobile host's authentication credential to the home AAA server 104, and waits for an authentication response from the home AAA server 104. An authentication delay thus results equal to a sum of the round-trip transmission time for the authentication request/response messages to travel between the mobile host 100 and the home AAA server 104, and the authentication processing time at the home AAA server 104. These authentication delays can affect the QoS, particularly in the case of long-distance, multi-hop transmissions between the foreign AP 102 and the home AAA server 104. Moreover, the home AAA server 104 can become overloaded from frequent handoffs between different access networks, such as what typically occurs with Internet roaming. Frequent overloads of the home AAA server may result in the authentication request being placed into a queue for a long time, further exacerbating the delay for the mobile host to authenticate to the new access network.